Flexible tubing is used in a wide range of applications, particularly in automated laboratory equipment. The tubing can act as a conduit for a variety of processing liquids and gases. It can also act as a conduit for the liquids and gases used to operate other pneumatic and/or hydraulic devices, such as, valves, pumps, etc.
Mechanical connectors are used to secure each end of the flexible tubing with a corresponding fluid source or port of the laboratory equipment. A connector structure that may be used to connect a flexible hose to the bulkhead of a tank is shown in U.S. Pat. No. 6,209,804, issued to Spriegel on Apr. 3, 2001. The connector of the '804 Patent includes a fitting having a barb and a compression nut that threads with a body portion of the fitting. The flexible hose is first assembled with the fitting so that the hose extends completely over and beyond the end of the barb. The compression nut is then threaded into engagement with the body portion of the fitting so that the flexible hose is clamped between the outer surface of the barb and the inner surface of the compression nut. The outer surface of the barb and the inner surface of the compression nut have generally the same contour so that they are substantially parallel with one another when assembled.
Connectors of the type shown in the '804 patent are prone to failure and are frequently the source of equipment breakdowns that require service calls. Failure modes vary, but are often the result of improper installation of the flexible tubing over the end of the barb on the fitting. Frequently, the flexible tubing is not completely driven over and beyond the barb to the necessary degree before the compression nut and fitting are threaded with one another. Over time, the end of the flexible tubing within the connector gradually becomes displaced thereby resulting in fluid leaks.
Another failure mode occurs when the connector is used with old tubing. Due to the repair or other service needs, the connector may be disassembled and the flexible tubing removed from engagement with the fitting. Unless the flexible tubing is itself defective, it is economical to reuse and reinstall the connector with the same tubing. However, the end portion of the tubing previously clamped between the fitting and compression nut may be permanently deformed as a result of its prior use. Such deformities may make it more difficult to reinstall the flexible tubing over and beyond the barb to the necessary degree for the connector to function properly. Even if the flexible tubing is properly engaged with the fitting, any weakening of the tubing walls may make it difficult for the fitting and compression nut to secure the tubing therebetween.